The present invention relates to a coupler for placing two or more fluid streams in communication, and, in particular, capillary scale fluid streams. Embodiments of the present invention provide a coupler for combining or interfacing two or more fluid streams in which one or more fluid streams entering or leaving the coupler has a flow rate of 1 to 200 nanoliters per minute and one or more fluid streams has a flow rate of approximately a 1 to 200 microliters per minute.
Analytical instruments often have several fluid streams, which fluid streams carry solutions to or from chromatography columns, pumps, valves, detector assemblies and the like. It is desirable to work with small volumes and to incorporate cleanly flushed geometries. It is sometimes necessary to split a small fluid stream from a larger fluid stream. Conventional fittings and coupling devices have large and often poorly swept internal volumes which may alter or compromise the results obtained when these devices are used.
A coupler for combining and or interfacing two or more fluid streams, where each stream is defined by a conduit, characterized by small internal volume is desired.
The present invention relates to coupler for placing two or more fluid streams in communication, and, in particular, capillary scale fluid streams. Embodiments of the present invention provide a coupler for combining two and, preferably, three or more fluid streams in which one or more fluid streams has a flow rate of 1 to 200 nanoliters per minute and one or more fluid streams has a flow rate of approximately 1 to 200 microliters per minute.
One embodiment of the present coupler comprises two or more conduits for transporting fluid. Each of the two or more conduits has at least one end defining an opening in said conduit, and each of the conduits has an axis running parallel to the flow of fluid through said conduit. The coupler further comprises a housing body having a first housing planar surface. The housing body holds the two or more conduits in alignment wherein conduits intersect the first housing planar surface. The axes of the conduits are substantially parallel, and at least one end of each conduit is aligned about said first housing planar surface. And, the coupler has a cap element having a cap planar surface. The cap planar surface is fixed to the first housing planar surface in sealed engagement. At least one of the first housing planar surface and the cap planar surface has a channel in fluid communication with the opening in the conduits. The channel allows two or more fluid streams, each fluid stream defined by one of said conduits, to be placed in communication.
Preferably, the coupler combines at least three fluid streams and these streams are defined by the conduits. These conduits are, preferably, fused silica capillary tubes. Fused capillary tubes typically have an outside diameter of 375 microns. Such tubes typically are available with selected internal diameters of 5 to 250 microns. Common tube internal diameters for the present invention comprise internal diameter of approximately 25 microns for 1-200 nanoliters per minute flow rates and approximately 50 microns for 1-200 microliters per minute flow rates.
Preferably, the housing body is an over-molded material such as a plastic. Preferred plastic materials are PEEK and/or PPS. The housing body of over molded plastic can accommodate fused silica tubes of different internal diameters to create fluid streams of different flow rates from a common pressure source. The cap element may be made of the same material or, where electrical contact is desired with the solutions which comprise the fluid streams, a metal or electrically conductive material. A metal cap element allows the fluid to be grounded or an electrical potential imposed on such fluid. Preferably, the ends of each conduit aligned about said first housing planar surface form a line and the channel is a groove in said first housing planar surface. This groove can readily be made by laser etching.
Preferably, the coupler further comprises a clamping assembly holding the first housing planar surface and the cap planar surface in sealed engagement. One preferred clamping assembly comprises one or more screws having threads engaging at least one of the cap element and the housing body. Preferably, the clamp assembly comprises a tab element, and the housing body has a flange for receiving the tab element. Each screw extends through an opening in the cap element and an opening in the tab element. Preferably, at least of the openings of the tab element and the cap element has threads to receive cooperating threads of the screw. The tab element is a circular ring or C-shaped ring.
A further preferred clamp assembly comprises a tab element, and a cap retaining element. The housing body has a housing flange for receiving the tab element. And, the cap element has an cap flange for engaging the cap retaining element. At least one of the cap element and tab element has an opening for receiving the other, and said cap element and tab element having cooperating thread surfaces. The cap element and tab element are joined by the opening for receiving the other with the cooperating threads.
Preferably, such clamp assembly comprises bearing means interposed between at least one of the group consisting of said tab element and cap element, on one hand, and the clamping element, on the other. The bearing means allows at least on of the cap element and tab element to rotate with respect to the clamp element.
Preferably, the housing body and the cap element have alignment elements.
A further embodiment of the present invention comprises a coupler for placing two or more fluid streams in communication. Such coupler comprises two or more conduits for transporting fluid. Each of the two or more conduits has at least one end defining an opening in the conduit. Each of the conduits has an axis running parallel to the flow of fluid through the conduit. The coupler further comprises a first housing body having a first housing planar surface. The first housing body holds one or more conduits in alignment wherein the axis of each conduit is substantially parallel, and at least one end of each conduit is aligned about the first housing planar surface. The coupler further comprises a second housing body having a second housing planar surface. The second housing body holds one or more conduits in alignment wherein the axis of each conduit is substantially parallel, and at least one end of each conduit is aligned about the second housing planar surface. The second housing planar surface is fixed to said first housing planar surface in sealed engagement with at least one of the conduits of the first housing body and the second housing body in fluid communication. The first and second housing bodies allow two or more fluid streams, each fluid stream defined by one of said conduits, to be placed in communication.
Preferably, at least one of the first housing body and the second housing body has two or more conduits. The two or more conduits are held in alignment wherein the axes of the conduits are substantially parallel, and at least one end of each conduit is aligned about the first housing planar surface. At least one of the first housing planar surface and the second housing planar surface has a channel in fluid communication with the openings in the two or more conduits. The channel allows three fluid streams, each fluid stream defined by one of said conduits, to be placed in communication.
Again, the conduits are, preferably, fused silica capillary tubes. Fused capillary tubes typically have an outside diameter of 375 microns. Such tubes typically are available with selected internal diameters of 5 to 250 microns. Common tube internal diameter sizes for the present invention comprise internal diameter tubes of approximately 25 microns for 1-200 nanoliters per minute flow rates and approximately 50 microns for 1-200 microliters per minute flow rates.
Preferably, the housing body is an over-molded material such as plastic. Preferred plastic materials are PEEK and/or PPS. The housing body of over molded plastic can accommodate fused silica tubes of different internal diameters to create fluid streams of different flow rates.
Preferably, the channel is a groove in said first housing planar surface.
Preferably, the coupler further comprises a clamping assembly holding the first housing planar surface and the second housing planar surface in sealed engagement.
A further embodiment of the present invention comprises a method for making a coupler for placing two or more fluid streams in communication. The method comprises the steps of providing two or more conduits for transporting fluid. Each of the two or more conduits has at least one end defining opening in the conduits. Each of the conduits has an axis running parallel to the flow of fluid through the conduit. The method further comprises the step of providing a housing body having a first housing planar surface. The first housing body holds one or more conduits in alignment wherein the axes of the conduits are substantially parallel, and at least one end of each conduit is aligned about the first housing planar surface. The method further comprises providing a cap element having a cap planar surface where the first housing body has two or more conduits. The cap element is fixed to said first housing planar surface in sealed engagement. In the alternative, the method comprises the step of providing a second housing body having a second housing planar surface. The second housing body holds one or more conduits in alignment wherein the axis of each conduit is substantially parallel, and at least one end of each conduit is aligned about the second housing planar surface. Where one of the first housing body or the second housing body has two or more conduits, at least one of the first housing planar surface, second housing planar surface and said cap planar surface has a channel in fluid communication with the openings in the two or more conduits. The channel allows two or more fluid streams, each fluid stream defined by one of said conduits, to be placed in communication.
Preferably, the housing body is comprised of an over-molded material which material is potted or molded about said conduits. A preferred over molded material is plastic. A preferred plastic is PEEK and/or PPS. The method has particular application where the conduits are fused silica capillary tubes. After the housing body is formed, the excess fused silica capillary tubes are trimmed flat with the planar surfaces. A groove forming a channel may be mechanically carved into the planar surface or laser etched.
These and other features and advantages will be apparent to those skilled in the art from an examination of the figures and a reading of the detailed description which follows.